Pilot and burner valve construction and method for an oven and the like



Feb. 6, 1968 c, BRANSON ET AL 3,367,572

PILOT AND BURNER VALVE CONSTRUCTION AND METHOD FOR AN OVEN AND THE LIKEOriginal Filed June 15, 1962 5 Sheets-Sheet l FlG-l co (\1 m 9 2 3- m Y.F I 1 T fir \i I *""m ll 8 Q q l N 9 Q I no N) g d' N O INVENTORS QCHARLES DAVID BRANSON JAMES ROBERT WILLSON m to 5 ARTHUR HARRY MALCOM r9* ATTORNEY Feb. 6, 1968 c. D. BRANSON ET AL 3,367,572

PILOT AND BURNER VALVE CONSTRUCTION AND METHOD FOR AN OVEN AND THE LIKEOriginal Filed June 15, 1962 5 Sheets-Sheet 2 l I I r I I44 I50 /l58 I60(I56 I55 I54 I52 4 INVENTORS CHARLES DAVID BRANSON F JAMES ROBERTWILLSON I ARTHUR HARRY MALCOM BYW I ATTORNEY Feb. 6, 1968 v c. D.BRANSON ET L 33 5 PILOT AND BURNER VALVE CONSTRUCTION AND METHOD FOR ANOVEN AND THE LIKE Originai Filed June 15, 1962 Sheets-Sheet 5 INVENTORSCHARLES DAVID BRANSON I JAMES ROBERT WlLLSON H6 5 ARTHUR HARRY MALCOMATTORNEY United States Patent 3,367,572 PILOT AND BURNER VALVECONSTRUCTION AND METHOD FOR AN OVEN AND THE LIKE Charles D. Branson,James Robert Willson, and Arthur Harry Malcom, Greensburg, Pa.,assignors to Robertshaw Controls Company, a corporation of DelawareOriginal application June 15, 1962, Ser. No. 202,789, now

Patent No. 3,233,830, dated Feb. 8, 1966. Divided and this applicationDec. 7, 1965, Ser. No. 578,915

Claims. (Cl. 236-68) ABSTRACT OF THE DISCLOSURE This disclosure relatesto a control system for a main burner means wherein a supply of fuel isadapted to be thermostatically controlled and passed to a safety valvemeans that is intermediate the thermostatic valve and the main burnermeans, the safety valve means only permitting the fuel to passtherethrough to the main burner means when the safety valve means sensesthat a heater flame is present at a pilot burner means. The pilot burnermeans has a first outlet means and is normally supplied with acontinuous flow of standby fuel to produce a small standby flame at thefirst outlet means thereof. The thermostatic valve means increases theflow of fuel to the pilot burner means to cause a large ignition flameat a second outlet means of the pilot burner means and a heater flamespaced from and below the ignition flame at a third outlet means of thepilot burner means whereby the heater means causes the safety valvemeans to open and permit fuel to flow to the main burner means to beignited by the ignition flame.

This application is a divisional patent application of its co-pendingparent application, Ser. No. 202,789, filed June 15, 1962, now issued asUS. Patent No. 3,233,830 on Feb. 8, 1966.

This invention relates to an improved pilot construction and an improvedburner valve construction and combination and method of operationthereof.

One of the features of this invention includes the use of a single pilotnozzle to produce a standby pilot flame when main burner ignition is notneeded and to produce an igniting pilot flame when main burner ignitionis required.

Another feature of this invention includes an inverted channel-shapedshield for a pilot construction which is eflective in maintaining astandby flame and an igniting flame to promote efficient igniion of themain burner when needed.

Another feature of this invention includes an inverted channel-shapedshield for a pilot construction which is eifective to heat athermostatic bulb in an eflicient manner when needed to open a burnervalve and is effective to maintain the thermostatic bulb sufficientlycool during standby conditions not to open the burner valve. The shieldalso promotes quick cooling of the thermostatic bulb when the ignitingflame is not produced.

Another feature of this invention provides a burner valve constructionin.which the closing spring action on the valve increases in strength asthe valve moves toward its valve seat and decreases in strength as suchvalve moves away from its valve seat.

Another feature of this invention provides a substantially snap-actionby the combined action of a local vaporizing thermostatic action in aliquid line to a thermostatic motor in combination with a spring actionon the valve which increases in strength as the valve closes and thethermostatic vapor condenses, and which spring action decreases instrength as said portion of thermostatic liquid vaporizes to receive aquick yielding impulse to open said valve as the liquid vaporizes.

Another feature of this invention provides a lever and springconstruction acting on a valve in a manner to apply an increasing valveclosing torque as the valve moves toward its valve seat and vice-versa.

An object of this invention is to provide a pilot construction havingone or more of the features herein disclosed.

Another object of this invention is to provide a burner valveconstruction having one or more of the features herein disclosed.

Another object of this invention is to provide a system for burneroperation having one or more of the features herein disclosed.

Another object of this invention is to provide a method of burnercontrol having one or more of the features herein disclosed.

Other objects are apparent from this description and the accompanyingdrawings in which:

FIGURE 1 is a diagrammatic representation of a burner system embodyingthis invention.

FIGURE 2 is a diagrammatic representation, on enlarged scale, of a partof the main gas burner, the pilot burner, the burner gas valve, and thethermostatic control for the gas valve.

FIGURE 3 is a perspective view of the nozzle construction for thedischarge conduit of the burner gas valve.

FIGURE 4 is an enlarged longitudinal vertical cross section of the pilotburner construction.

FIGURE 5 is a view of a portion of FIGURE 2 with the valve in openposition.

FIGURE 6 is an end view of the main gas burner and pilot burner.

FIGURE 7 is an enlarged cross section of the valve actuating means shownin FIGURE 2 taken from the opposite side.

FIGURE 8 is a top view of the valve actuating lever.

FIGURE 9 is a top view of the supporting fulcrum lever.

FIGURE 10 is an enlarged view of the fulcrum c0n struction.

Certain words indicating direction, relative position, etc., are used inthis application for the sake of brevity and clearness. However, suchwords are not intended as limitations and apply only to theillustrations in the drawings. The actual constructions used may havedifferent directions, relative positions, etc. Words such as vertical,horizontal, upper, lower, etc., are types of words which are used inthis manner.

Referring first to FIGURE 1, an oven 20 may be provided with a main gasburner 22, a pilot construction 24, a main burner gas valve construction26, a gas supply pipe 28. A thermostatic control construction 30 mayhave a thermostatic bulb 32 in the oven 20 which causes saidthermostatic control construction 30 to control the heating action ofthe burner 22 to produce desired temperatures in the oven 20. A main gasvalve 33 may control the flow of gas to the system shown in FIGURE 1.

The pilot construction 24 may be of a character such that it produces astand-by pilot flame 34, FIGURE 4, incapable of igniting the burner 22,and an igniting flame 36 capable of igniting the burner 22.

The stand-by pilot flame 34 is incapable of heating the thermostaticbulb 35 sutficiently to cause such bulb 35 to cause gas to be suppliedto the main burner 22 by the gas valve 26. The flame 36 is of such size,or construction, or shape, that it is capable of heating thethermostatic bulb 35 to cause gas to be supplied to the burner 22 by thevalve 26 so the burner may be ignited by the igniting flame 36.

The pilot construction 24 may include a nozzle 38, which receives gasfrom the pipe 40 and discharges it through an orifice 42 in sufiicientquantity to produce the stand-by flame 34 under one type of control, andto produce the igniting flame 36 under a different type of control.

The gas is discharged from the orifice 42 as a jet 44 which entrains aquantity of atmospheric air entering through one or more orifices 46 inthe side of connector 48.

When the stand-by flame 34 is to be produced, the gas entering thenozzle 38 is of limited quantity and pressure so that only a smallamount of gas and air are fed to the shield 50. The shield 50 may beinverted channel-shaped in cross section, and may have a downwardly openelbow 52 which guides the gas and air mixture to the first pilot burneraperture 54 through which the limited amount of gas and air pass andform the stand-by pilot flame 34. The aperture 54 may be provided with asmall hood 56 which aids in controlling the formation of the flame 34.

The stand-by calibrating valve 58, FIGURE 1, may be adjusted so that thestandby pilot flame 34 is a small blue flame, and the small blue flameis the calibration indicator to show that the pilot flame has beenadjusted to the desired size.

The production of the standby pilot flame on top of the shield 50prevents undesired heating of the thermostatic bulb 35 during thestandby conditions.

The hood 50 has a downwardly slanting channel 60 with an open end 62 andone or more additional small hoods 64, and igniting flame apertures 65.The construction is such that when a larger quantity of gas is fedthrough the nozzle 38, by the thermostat construction 30, then theigniting flame 36 is produced, which burns at 36, 36A and 36B as gas andair mixture are fed under the small hood or hoods 64, and out of the end62, and these i niting flame portions are sufficiently high to ignitethe burner gas which is discharged through the burner orifices 66. Ifdesired, the orifices 66 may be slightly downwardly slanted along theside 68 of the burner. The end 70 of the burner 22 may also be providedwith orifices 66 which carry the ignition to the other similar side 68Aof the burner.

The igniting flame 36 burns at 36B, under the end of the hood 50, sothat the flame 36B heats the bulb 35 either by direct contact, orbecause of close proximity, so that a portion of the liquid mercury, orother thermostatic fluid in the bulb 35, has its liquid phase changed toa gaseous phase to produce a quickly increasing thermostatic fluidpressure in the thermostatic fluid enclosure of which the bulb 35 is apart. The tube 72 and thermostatic motor 74 form the remainder of thethermostatic fluid enclosure.

When the ignition flame 36, 36A and 36B ceases to be produced, thechannel-shaped shield or hood promotes the upward flow of cooling air incontact with the thermostatic bulb 35 to cause quick cooling action ofthe bulb 35. The notches 51 at the elbow 50 promote this cooling action.

The bulb 35 is connected by a tube 72, which forms a part of thethermostatic fluid enclosure, and which is connected to the thermostaticmotor 74, in the burner gas valve construction 26, to cause burner gasto be supplied by the burner gas valve construction 26 to the burner 22in response to temperatures produced by the burner 22, as elsewherefurther described. The size of the igniting flame 36, 36A and 36B may beregulated by an igniting flame regulating valve 76, FIGURE 1.

The construction is such that when the temperature in the oven 20, asproduced by the burner 22. is below a selected level, the thermostaticbulb 32 causes the thermostatic construction 30 to feed an ignitingflame producing amount of gas through the igniting gas pipe 78, FIG-URE 1. The pipe 78 is connected to the pilot burner pipe 40. This causesthe large igniting flame 36, 36A and 36B to be produced in the pilotconstruction 24. This heats the pilot thermostat bulb 35, which in turnactuates or expands the thermostatic motor 74 and causes burner gas tobe fed by the burner gas valve construction 26 to the burner 22.

This heats the oven 20 until the temperature in the oven 20 reaches thedesired maximum, at which time the thermostatic bulb 32 causes pilot gasto cease to be fed through the pipe 78, which in turn causes theigniting pilot flame 36, 36A and 368 to cease to be produced. Thispermits the pilot bulb 35 to cool and thereby restore the thermostaticfluid to the liquid phase throughout the fluid enclosure, and to causethe burner gas valve construction 26 to cease feeding burner gas to theburner 22.

The thermostatic motor 74 may include a pair of telescoped resilientcup-shaped diaphragms 75A and 75B, which are sealed together at theflanges 75C to form an expandable motor 74 into which the liquid mercuryis forced when the mercury in bulb 35 is vaporized.

A suitable bracket construction 80, of any desired shape, may beprovided to hold the hood 50, the nozzle construction 49 which holdsnozzle 38, and the bulb 35 adjacent to the burner 22. If desired, thisbracket construction 80 may be secured by the flange 82 to the top ofthe burner by one or more screws 84.

The thermostatic control construction 30, FIGURE 1, may be of anysuitable character capable of controlling the flow of igniting burnergas through the pipe 78 in response to the temperatures registered bythe thermo static bulb 32. A suitable knob 36 may be included, whichadjusts the thermostat valve construction 88, so the construct-ion 88causes gas to be fed from the pipe 90 and gas supply 28, through theregulating valve 76 and pipe 78 to the pipe 40 and nozzle 38.

Standby pilot gas may be fed through standby pipes 92 and 94, and thestandby flame regulating valve 58, t0 the pipe 40 and from thence to thenozzle 38. The regulating valves 58 may be supported on the thermostatcasing 96, or the pipes 92 and 94, and valve 58 may be entirely separateand independent from the casing 96, as desired.

The thermostat control construction may feed standby gas continuouslythrough the pipes 92, 94 and 40, as regulated by an adjustable orificevalve 58, so the standby flame 34 only is formed when no gas is fedthrough the pipes 90 and 78 when the thermostat valve 88 is closed bybulb 32 when the oven 20 is sufliciently warm. However, when the ovencools below a desired level, the bulb 32 opens the valve 88 and feeds alarger amount of gas through pipes 96, 78 and 40, and regulating valve78 to produce the igniting flame 36, 36A and 36B.

The burner gas valve construction 26 may have a burner gas dischargeconnection 100, which has an adjustable orifice 102, which dischargesthe burner gas in the form of a jet stream past the well known gas andair mixing construction 104. The rate of discharge at the orifice 102may be regulated by turning the gas connector 100, to cause the threadedconstruction 101 to regulate the jet 102, as desired.

The burner gas valve construction 26 may have a discharge valve seatconnected in gas flow relationship to the burner 22, as by the connector110, which discharges into the nozzle construction 100.

The jet construction may include a lower passageway 100A which isthreaded on the upper portion 101 of connector and is adjustable up anddown by said threaded construction.

A jet piece 100B has a larger bore 100C and the minimum flow passage100D. The upper end 100E of construction 100 has an internal conicalbore 100E which may seal against the upper conical end 100G to force allthe gas through passage 100D.

The conical bore 100H is tapered so it does not seat against the upperslanting ends 100] of wings 100K so a tight seal may be formed at 100B.

The wings 100K are driven in the bore 100L and against the shoulder100M.

The construction 100 may be turned to its lowest position to produce aminimum discharge through passage 100D or construction 100 may beadjusted upwardly by the threaded construction to produce a bypassbetween 100F and 1006 so a larger amount of gas may be fed to the mixer104.

A valve 112 may seat on the valve seat 108, and, if desired, may have asealing disc 114 to engage the seat 108 in effective sealingrelationship.

A guide pin 116 may have a head 118 to guide valve 112 through themedium of a cylindrical opening 120. The downward movement of the valve112 may be limited by the end wall 122 of the opening 120 when the wall122 engages the head 118. The pin 116 may be fluted and driven into thecylindrical opening 124 of the valve casing 126, to the proper levelproperly to limit the downward movement of valve 112.

The thermostatic motor 74 may have means to move the valve 112 towardsaid valve seat 108 when the igniting flame 36, 36A, 36B, or a similarflame, ceases to be produced. Such means may also move the valve 112away from the valve seat 108 when such igniting flame 36, 36A and 36B isproduced. This action is indirectly in response to the control of theignition gas by the thermostatic bulb 32 and thermostat 30 in responseto the temperature in oven 20. The action maintains the temperature inthe oven 20, or other heated object, within selected temperature limits.

The means to move the valve 112 may include a spring construction 128,FIGURE 7, acting to aid in moving the valve 112 toward the valve seat108, and increasing the valve seating strength as the valve 112 movestoward the valve seat 108 and decreases in strength as said valve 112moves away from said valve seat 108.

The construction is such that the valve 112 is qiuckly opened when aportion of the mercury in bulb 35 is vaporized and is quickly closedwhen the vaporized portion is cooled and condensed. This quick openingand closing of valve 112 is in response to the existence or nonexistenceof ignition flame 36, 36A, 3613, or similar control flame.

The thermostatic motor 74, tube 72 and bulb 35 form a thermostatic fluidcasing which is heated by the igniting flame 36, 36A, and 36B. A portionof the thermostatic fluid in the thermostatic casing, such as in bulb35, may change phase when it is heated by said igniting flame 36B orsimilar flame. For example, the bulb 35 and the tube 72 and thethermostatic motor 74 may contain mercury in liquid form at normalatmospheric temperature, and the fluid casing so produced by thesemembers may be charged with liquid mercury through the opening 130,FIGURE 7, after which the ball 132 may be welded to the opening 130, onthe motor head 134, which is secured to the diaphragm 75B.

A suitable wire 136 may be placed in the tube 72 to reduce the amount ofmercury used in the tube 72, and may be chosen of such material, that itmay compensate for the expansion and contraction of the tube 72 andliquid mercury due to surrounding temperatures, so such atmospherictemperature changes, and other temperatures which do not vaporizemercury (below 700 F. more or less) do not affect the valves 112.

The portion of the thermostatic fluid, or mercury, which is in the bulb35 may change phase. For example, the liquid mercury in bulb 35 may bevaporized at temperatures of 700 F., more or less, and the production ofthis vapor causes a quick and elastic movement of the ball 132 toproduce a substantially snap-acting opening and closing of the valve112, depending upon the change from liquid mercury to mercury vapor andvice-versa.

The valve moving means or spring construction 128 may include a valveactuating lever 136 having a lever fulcrum 138 and a valve actuatingportion 140, Which are separated from each other. The thermostatic motor74 has means, such as the ball 132, to move the lever 136 and valve 112toward and away from the valve seat.108.

The spring construction 128, may include a relatively strong compressionspring 142 which cooperates with the lever 136 to move the valve 112toward the seat 108. The spring construction 128, which may include therelatively strong spring 142, with or without an additional relativelyWeak compression spring 144, cooperates with the lever 136 to move thevalve 112 toward the seat 108. The spring construction 128 increases'invalve seating strength as the valve 112 moves toward the valve seat 108and decreases in strength as the valve 112 moves away from the valveseat 108.

A lost motion notch may be provided in valve 112 to permit the lever 136to impart an additionally quick opening motion to the valve 112 as themercury starts to vaporize.

A supporting fulcrum 146 cooperates with the lever fulcrum 138 to holdthe lever 136 in pivoting position The lever fulcrum 138 may behook-shaped as at 148 and engages the knife edge of the stationary orsupporting fulcrum 146. The compression spring 142 pulls the hook typefulcrum 138 tightly against the stationary or supporting fulcrum 146, ina rightward direction in FIG- URES 7 and 10.

The supporting fulcrum 146 may be adjustable up and down, for example,to adjust and calibrate the opening and closing action of valve 112. Forexample, the supporting fulcrum 146 may be carried by a fulcrum lever150 which is adjustable to adjust the supporting fulcrum 146.

The lever 150 may be pivoted by hooks 152 inserted in openings 154 inthe valve casing end wall 155. The lever 150 is adjustable by the pin156, which may be longitudinally adjusted, as by the threadedconstruction 158 which has a screw head 160, for longitudinalengagement.

A suitable valve casing cover 157 may be bolted on the end wall 155after the lever 150 has been positioned. The cover 157 may carry thethermostatic motor 74 so the ball 132 engages lever 136.

The compression spring 142 has a first spring part, such as one end 161which engages the lever 136, through the medium of a disc 162 whichengages the lever 136 at a first spring fulcrum 164.

A second spring part 166, which may be the other end of the spring 142,may engage a second spring fulcrum 168, which is carried at the end ofthe lever 150.

The spring fulcrums 164 and 168 are so located to produce a valveclosing torque, as indicated 'by the dotted line 170 in FIGURE 7, whichextends from the fulcrums 138 and 146 to the right angled intersection172 with the extended line 174 fiom the spring fulcrums 164 and 168.

The first spring fulcrum 164 swings about the arc 176 which is centeredabout the fulcrums 138 and 146. The fulcrum 168 is stationary during theoperation of the device and is movable only for adjustment purposes.Therefore, the extension line 174 moves toward the fulcrums 138 and 146as indicated at 174A as the valve 112 moves away from the valve seat108. Hence the intersection 172 likewise moves towards the fulcrums 138and 146, as indicated at 172A as the valve 112 moves away from the valveseat 108. The line 170 is indicative of the torque produced by therightward pull of the line 174 (in FIGURE 7) due to the compressionspring 142. It produces a counter-clockwise torque about the fulcrums138 and 146 which increases in length and strength as valve 112 movestoward the seat 108, and decreases in length and strength as the valve112 moves away from the valve seat 108.

This increase in spring torque 170 as the valve 112 moves toward thevalve seat 108 causes a quick closing movement of the valve. Conversely,the decrease in spring torque 170 as the valve moves away from the valveseat 108 causes the valve 112 to have a quick opening movement. Thisaction is amplified by the resiliency of themercury vapor in bulb 135.

The supporting fulcrum 168 cooperates with the adjacent spring fulcrumand is adjustable by the pin 156' to calibrate the action of valve 112.The fulcrum 168 is carried by the lever 150, which is adjustable by thepin 156 about the fulcrums 152 to adjust the supporting fulcrum 168.

The lever 150 is held in locked position by the thrust: of the ball 132,the openings 154, and the pin 156.

The lever 150 may be adjusted by the pin 156 to cause any relativemovement between the line 174 and the fulcrums 138 and 146. For example,it may be preferred to cause the extension line 174 to be at, or justslightly below the fulcrums 138 and 170 when the valve 112 is: in thedownward fully opened position 112A, and to be a relatively longdistance, such as at 172, when the valve 112 is in the fully closed andfull line position illustrated in FIGURE 7.

The lever 136 may be made of a stamping, such as:

shown in FIGURE 8. The lever 136 has extension shoulders 180 which carrya pair of hook fulcrums 138, which act in unison against the pair ofknife fulcrums; 146, shown in FIGURE 9. FIGURE 9 shows the lever 150 tobe a relatively flat piece of metal with shoulders: or hooks 152 carriedby an extension 182. The spring: supporting fulcrum 168 is shown at theright end of FIGURE 9. A downward extension 184 is punched into thelever 150 to engage the pin 156. A strengthening; ridge 186 is formed tomake the lever 151) rigid.

If desired, the spring 142 may have a spring strength of 6 pounds, moreor less at its normal load. The spring: 144 may be relatively weak, andmay have a spring: strength of 1.5 ounces, more or less, when at itsnormal load. The spring 142 therefore provides a very substantial upwardpush on the valve 112 when the valve closes- It is strongest in valveclosing strength or torque when. valve 112 is in the fully closedposition as shown in full lines in FIGURE 7 and has a small valveclosing torque: when the valve 112 is open.

The parts which contact the mercury, if used, may be made of materialwhich is not affected by the mercury. For example, the bulb 35, tube 72,wire 136 and. the mercury contacting parts of motor 74 may be made ofstainless steel, or the like.

It is thus to be seen that this invention provides new and useful pilotconstructions, burner gas valve constructions, and combinations thereof.Also new and useful methods of control are provided.

In the fully closed position of the valve 112, and in. the fullyretracted position of the ball 132, not shown, the ball 132 is slightlyspaced from the lever 136 to permit the full closing force of the spring142 to act on the valve 112.

The dotted line position of lever 136 in FIGURE 7 is not its lowestposition when the valve 112 is fully opened. Such lowest position isbelow the dotted line showing. Also the line 174 approaches the fulcrums138 and 146 to a position closer than 172A when the valve 112 is infully open position. Hence the counterclockwise torque of lever 136 isless than the torque at 172A when valve 112 is in fully open position.

While the form of the invention now preferred has been disclosed asrequired by statute, other forms may be used, all coming within thescope of the claims which follow.

What is claimed is:

1. In a fuel control system, a pilot burner means having a first outletmeans to normally issue a small standby flame during normal flow of fuelto said pilot burner means, said pilot burner means having a secondoutlet means spaced from said first outlet means, and means forincreasing the flow of fuel to said pilot burner means to create a largeignition flame at said second outlet means for ignition purposes, saidpilot burner means having a third outlet means spaced from and belowsaid first and second outlet means to produce a heater flame at saidthird outlet means only when said increased flow of fuel is directed bysaid fuel flow means to said pilot burner means.

2. In a fuel control system as set forth in claim 1, said pilot burnermeans carrying a heater flame detector adjacent said second outletmeans.

3. In a fuel control system as set forth in claim 2, said heater flamedetector comprising a temperature sensing bulb.

4. In a fuel control system as set forth in claim 1, a main burnermeans, said pilot burner means being disposed adjacent said main burnermeans to ignite said main burner means with said ignition flame.

5. In a fuel control system as set forth in claim 4, and meansresponsive to said heater flame adapted to cause fuel to flow to saidmain burner means.

6. In a fuel control system as set forth in claim 5, said pilot burnermeans being positioned so that said heater flame is disposed remote fromsaid burner means.

7. In a fuel control system as set forth in claim 1, a main burner, asafety valve for supplying fuel to said main burner, said pilot burnerbeing disposed adjacent said main burner to ignite said main burner withsaid ignition flame, and means for sensing said heater flame to opensaid safety valve to direct fuel to said main burner to be ignited bysaid ignition flame.

8. In a fuel control system as set forth in claim 7, said pilot burnermeans including a temperature sensing means that senses said heaterflame and causes opening of said safety valve.

9. In a fuel control system as set forth .in claim 7, said fuel flowmeans being thermostatically controlled in response to the temperatureeffect of said main burner.

10. In a fuel control system as set forth in claim 1, said pilot burnermeans including a flame shield against which said fuel impinges whensaid fuel is directed to said pilot burner means, said flame shieldhaving a free end that defines said third outlet means and having twoopenings passing therethrough which respectively define said first andsecond outlet means.

References Cited UNITED STATES PATENTS 1,842,337 1/1932 Te Pas 236682,999,535 9/1961 Alger 158-113 3,078,916 2/1963 Loveland 158-1153,146,823 9/1964 Loveland 158123 3,155,143 11/1964 Jackson et al. 1581133,166,248 1/1965 Fleer 23668 EDWARD J. MICHAEL, Primary Examiner.

